1. Field of the Invention
This invention relates generally to a high output halogen incandescent lamp and in particular to a multi-segment filament halogen lamp with four segments circling a fifth segment positioned in the center and located on the lamp axis.
2. Description of Related Art
In halogen lamps where multi-segment filaments are used, the filament segments are parallel to the lamp/fixture axis and symmetrically arranged in a circular pattern around the axis. Single linear arrangements of segments as well as staggered arrangements are often used.
The efficiency of a filament depends on its loading (lumens/watt), and the efficiency is affected by the degree of self-blocking of the radiated light within the filament because of its particular geometric arrangement. There are two conflicting forces at play. To best approximate the ideal light source (point source), a filament must be compact. To minimize the self-blocking effect, radiant elements must be spread out. An efficient, finite filament must consider and blend both effects. The filament geometry must mesh well with the fixture's reflector and other optical components in order to extend efficiency beyond the lamp to the lamp/fixture system, which places further restrictions on the filament structure design.
Prior art patents include U.S. Pat. No. 4,766,339 issued Aug. 23, 1988 to William L. Berry et al. and assigned to GTE Products Corp. which discloses an electric lamp including an envelope having a sealed end portion with a reinforced filament structure within the envelope having a plurality of several individual coated tungsten filaments connected in series, a first insulative bridge located within the envelope between the filament structure and the sealed end portion, first and second lead-in conductors coupled to the filament structure, first and second support wires extending within the envelope adjacent to the first and second conductors for supporting the filament structures, and reinforcement means in the form of a pair of platinum-clad molybdenum wire members being disposed at a location below the first insulative bridge and above the sealed end portion. The electric lamp preferably includes a halogen atmosphere within the envelope. However, although there are multi-segment filaments known as a C13 type filament, it does not relate filament geometry to fixture/reflector geometry.
U.S. Pat. No. 5,268,613 issued Dec. 7, 1993 to David W. Cunningham and assigned to Gregory Esakoff which discloses an incandescent illumination system for projecting a beam of light comprising a concave reflector and an incandescent lamp having a plurality of linear, helically-wound filaments arranged with their longitudinal axis substantially parallel with and spaced substantially around the longitudinal axis of the concave reflection. A substantial portion of the light emitted by the lamp impinges on, and is redirected by the reflector to project a beam of light substantially parallel with the longitudinal axis of the reflector. However, invention is based on coupling filament geometry to that of the fixture, and its four segments tend to have a four-lobed beam. The central segment of the present invention fills-in such lobed beams.
U.S. Pat. No. 6,798,138 issued Sep. 28, 2004 to Rolf Gervelmeyer et al. and assigned to Koninklijke Philips Electronics, N.V., discloses a halogen incandescent lamp for motor vehicles with an elongated bulb which is closed at one end and has a vacuum-tight pinch seal at the other end with a lamp cap connected to the pinch seal and with current supply leaders which are passed through the pinch seal to the incandescent element, and an annular optical absorption filter is provided at the closed end of the bulb with a coating of at least one layer of cobalt aluminate. Although illumination properties are improved, it does not provide a high output. The coating on the bulb filters out higher wavelengths resulting in a lamp output that is more blue/white in an attempt to mimic the spectrum of the new discharge headlights.